Do you have your own plumbing equipment?

You will likely have some of your own equipment but perhaps not all of it. And, that's okay to admit!

If you do not have all of your own plumbing equipment you could answer like this: "I have a few of my own tools, mainly everything that is needed for a basic plumbing job. How do you feel about providing the more complex tools?" This way, you can gauge the interviewer's willingness to assist you with equipment.

If you do have all of your own equipment be sure to say so but also ask if they prefer you use their equipment or provide your own.